"""Base class for SharedKeyDB and VerifierDB."""



import anydbm

import thread



class BaseDB:

    def __init__(self, filename, type):

        self.type = type

        self.filename = filename

        if self.filename:

            self.db = None

        else:

            self.db = {}

        self.lock = thread.allocate_lock()



    def create(self):

        """Create a new on-disk database.



        @raise anydbm.error: If there's a problem creating the database.

        """

        if self.filename:

            self.db = anydbm.open(self.filename, "n") #raises anydbm.error

            self.db["--Reserved--type"] = self.type

            self.db.sync()

        else:

            self.db = {}



    def open(self):

        """Open a pre-existing on-disk database.



        @raise anydbm.error: If there's a problem opening the database.

        @raise ValueError: If the database is not of the right type.

        """

        if not self.filename:

            raise ValueError("Can only open on-disk databases")

        self.db = anydbm.open(self.filename, "w") #raises anydbm.error

        try:

            if self.db["--Reserved--type"] != self.type:

                raise ValueError("Not a %s database" % self.type)

        except KeyError:

            raise ValueError("Not a recognized database")



    def __getitem__(self, username):

        if self.db == None:

            raise AssertionError("DB not open")



        self.lock.acquire()

        try:

            valueStr = self.db[username]

        finally:

            self.lock.release()



        return self._getItem(username, valueStr)



    def __setitem__(self, username, value):

        if self.db == None:

            raise AssertionError("DB not open")



        valueStr = self._setItem(username, value)



        self.lock.acquire()

        try:

            self.db[username] = valueStr

            if self.filename:

                self.db.sync()

        finally:

            self.lock.release()



    def __delitem__(self, username):

        if self.db == None:

            raise AssertionError("DB not open")



        self.lock.acquire()

        try:

            del(self.db[username])

            if self.filename:

                self.db.sync()

        finally:

            self.lock.release()



    def __contains__(self, username):

        """Check if the database contains the specified username.



        @type username: str

        @param username: The username to check for.



        @rtype: bool

        @return: True if the database contains the username, False

        otherwise.



        """

        if self.db == None:

            raise AssertionError("DB not open")



        self.lock.acquire()

        try:

            return self.db.has_key(username)

        finally:

            self.lock.release()



    def check(self, username, param):

        value = self.__getitem__(username)

        return self._checkItem(value, username, param)



    def keys(self):

        """Return a list of usernames in the database.



        @rtype: list

        @return: The usernames in the database.

        """

        if self.db == None:

            raise AssertionError("DB not open")



        self.lock.acquire()

        try:

            usernames = self.db.keys()

        finally:

            self.lock.release()

        usernames = [u for u in usernames if not u.startswith("--Reserved--")]

        return usernames